Of the long list of 176 Marilyn’s in England, there is only one of its type on Dartmoor. That lonely peak is High Willhays (SX 580892 621m a.s.l.). A Marilyn doesn’t have to be any particular height but it does need to have an elevation of 150m or more of relative height.
High Willhays does have a slightly lesser peak (Yes Tor 619m a.s.l.) and indeed many other linked Dartmoor peaks that do not allow for a fall of over 150m however it exists as a Marilyn due to the fact that it is the highest point on Dartmoor and Dartmoor’s elevation is over 150m above the surrounding countryside.